- Human pathology

Home > D. General pathology > Environmental and occupational diseases > psoralen


Monday 8 September 2014


Psoralen (also called psoralene) is the parent compound in a family of natural products known as furocoumarins. It is structurally related to coumarin by the addition of a fused furan ring, and may be considered as a derivative of umbelliferone.

Psoralen occurs naturally in the seeds of Psoralea corylifolia, as well as in the common fig, celery, parsley and West Indian satinwood.

It is widely used in PUVA (= psoralen + UVA) treatment for psoriasis, eczema, vitiligo, and cutaneous T-cell lymphoma.


Psoralen is a mutagen, and is used for this purpose in molecular biology research.

Psoralen intercalates into the DNA and, on exposure to ultraviolet (UVA) radiation, can form covalent interstrand cross-links (ICL) with thymines preferentially at 5’-TpA sites in the genome, inducing apoptosis.

Psoralen plus UVA (PUVA) therapy has shown considerable clinical efficacy. Unfortunately, a side effect of PUVA treatment is a higher risk of skin cancer.

An important use of psoralen is in PUVA treatment for skin problems such as psoriasis and (to a lesser extent) eczema and vitiligo. This takes advantage of the high UV absorbance of psoralen. The psoralen is applied first to sensitise the skin, then UVA light is applied to clean up the skin problem.

Psoralens are also used in photopheresis, where they are mixed with the extracted leukocytes before UV radiation is applied.

Tanning accelerators

Despite the photocarcinogenic properties of psoralen, It had been used as a tanning activator in sunscreens until 1996.

Psoralens are used in tanning accelerators, but users should keep in mind that psoralen increases the skin’s sensitivity to light. Some patients have had severe skin loss after sunbathing with psoralen-containing tanning activators.

Patients with lighter skin colour suffer four times as much from the melanoma-generating properties of psoralens than those with darker skin.

Inactivation of infectious pathogens

The synthetic amino-psoralen, amotosalen HCl, has been developed for the inactivation of infectious pathogens (bacteria, viruses, protozoa) in platelet and plasma blood components prepared for transfusion support of patients. The technology is currently in routine use in certain European blood centers


- The gene expression profile of psoralen plus UVA-induced premature senescence in skin fibroblasts resembles a combined DNA-damage and stress-induced cellular senescence response phenotype. Borlon C, Debacq-Chainiaux F, Hinrichs C, Scharffetter-Kochanek K, Toussaint O, Wlaschek M. Exp Gerontol. 2007 Sep;42(9):911-23. PMID: 17574363